Radar Sensor Reference Grid Using Talbot Effect
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Solution Overview
Problem
Conventional radar sensors in automotive and robotic applications face reliability issues due to interference from reference objects, which can lead to undetected persons and increased collision risks, as the distance and echo strength from reference objects overpower the detection of humans, limiting the maximum detection range and increasing costs with actuator systems.
Innovation Solution
A radar sensor system utilizing two grids with regularly spaced metallic wires, where the second grid is positioned at Talbot plane intensity zeroes, allowing wavelength switching to control echo visibility, ensuring reliable operation by adjusting echo power and minimizing interference from reference objects while maintaining sensitivity to human detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the reference object is placed close to the transceiver to ensure detection, then the reference object echo strength increases, but the maximum detection distance for persons is reduced due to the strong reference echo concealing weaker person echoes
Solution Approach 1:
The patent changes the physical parameters of the reference object by using a grid structure with specific grid constants and spacing. The grid is positioned at a Talbot plane distance L = n*d²/λ from the transceiver, where the diffraction pattern creates intensity zeroes that minimize the reference echo strength. This parameter optimization allows the reference object to be placed at an optimal distance that provides sufficient echo for reliability verification while maintaining adequate detection range for persons.
Solution Approach 2:
The patent replaces the conventional mechanical approach of simply placing a reference object at a fixed distance with a physics-based solution using diffraction and interference phenomena. By utilizing the Talbot effect and positioning the grid at specific distances where intensity zeroes occur, the system automatically minimizes reference echo interference without requiring mechanical adjustment mechanisms.
2Length of stationary object
If the reference object is placed far from the transceiver to increase detection distance, then the reference object echo strength decreases, but detection of the reference object may be thwarted by the presence of a person between the radar sensor and the reference object
Solution Approach 1:
The patent optimizes the grid parameters (grid constant d, spacing L, and distance L = n*d²/λ) to create a reference echo that is sufficiently strong for reliable detection even when the grid is placed at an optimal distance that allows adequate person detection range. The Talbot plane positioning ensures the reference echo remains detectable while maintaining maximum detection distance.
3Object-generated harmful factors
If an actuator is provided to move the reference object into and out of the propagation path, then the interference from the reference object can be controlled, but the cost and complexity of the robot system increases
Solution Approach 1:
The patent extracts the harmful interference component by using a grid structure that naturally produces minimal echo through diffraction and interference effects. The grid is positioned at a Talbot plane where intensity zeroes occur, effectively removing the reference echo interference without requiring mechanical movement or complex control systems.
Solution Approach 2:
The grid structure self-regulates the reference echo strength through its physical positioning at the Talbot plane. The diffraction and interference phenomena automatically minimize the echo without requiring external control mechanisms, actuators, or power consumption for adjustment.
4Object-generated harmful factors
If an actuator is provided to move the reference object, then the reference echo interference can be managed, but the cost of the robot system increases
Solution Approach 1:
The patent eliminates the need for expensive actuator systems by using a stationary grid structure that leverages physical diffraction and interference effects. The grid is positioned at a Talbot plane distance L = n*d²/λ where the reference echo is naturally minimized, removing the need for mechanical movement components and associated costs.
Solution Approach 2:
The grid structure provides self-regulating reference echo minimization through its fixed positioning at the Talbot plane. The system uses passive physical phenomena (diffraction, interference) rather than active mechanical adjustment, significantly reducing system cost while maintaining effectiveness.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enhances the reliability of radar sensor operation by reducing background noise and maintaining sensitivity to human detection, allowing for safer robotic and automotive applications by effectively distinguishing between reference object echoes and human presence.
Implementation Method 1
a transceiver unit which is operable to emit a radar beam at at least two different wavelengths along a beam path in an outgoing direction and receiving radar radiation along said beam path in an incoming direction
Implementation Method 2
the transceiver unit (10) is operable at a wavelength λ which satisfies n being an integer. The invention makes use of the so-called Talbot effect: when monochromatic radiation is incident on a grating having a grating constant d, an intensity distribution of the radiation behind the grating will result in which in a plane (referred to subsequently as the Talbot plane) at a distance L =2d/λ 2 from the grating, zeros of intensity will appear at a distance d from each other
Data Source
Figure 1~3
Figure 4~5
AI summary
A radar sensor (6, 7) comprises a transceiver unit (10) for emitting a radar beam (13) along a beam path in an outgoing direction and receiving radar radiation along said beam path in an incoming direction. A reference object is placed in said beam path for redirecting part of the outgoing radar beam (13) in the incoming direction. The reference object comprises two identical grids (14, 17), each grid (14, 17) being formed of regularly spaced elements (15) arranged at a distance d from each other in a first direction perpendicular to the beam path. The grids (14, 17) are spaced from one another along the beam path by a distance L, and the transceiver unit (10) is operable at a wavelength λ which satisfies (I), n being an integer.